Cardiac fibroma

Cardiac fibroma, also known as cardiac fibromatosis, are benign congenital cardiac tumours that usually manifest in children. 

Epidemiology

Cardiac fibroma is a tumour that primarily affects children (most cases is detected in infants or in utero). They are the second most common benign primary cardiac tumour in children after cardiac rhabdomyoma and second most frequent fetal cardiac tumour ².

Clinical presentation

Cardiac fibromas are often associated with arrhythmias which can be a presenting feature.

Pathology

Microscopic appearance

Cardiac fibromas represent a collection of fibroblasts interspersed among large amounts of collagen (some authors believe that this tumour is a hamartoma rather than a neoplasm).

Macroscopic appearance

They are well-defined, solitary, intramyocardial lesions with smooth margins and usually large, with a mean diameter of ~5 cm and may obliterate the ventricular cavity. They almost always arise in the ventricles, most commonly in the ventricular septum and left the ventricular free wall. Unlike many primary cardiac tumours, fibromas usually have no foci of cystic change, haemorrhage, or necrosis. Calcification is a common finding.

Associations

There is an increased prevalence of cardiac fibromas in Gorlin syndrome.

Radiographic features

CT

On CT, cardiac fibromas are homogeneous soft-tissue masses that are usually sharply marginated, but also can be infiltrative. Dystrophic calcification is common.

MRI

Due to their dense, fibrous nature, the tumours are usually homogeneous and hypointense on T2-weighted MR images and isointense relative to muscle on T1-weighted images. They often demonstrate little or no contrast material enhancement.

Differential diagnosis

• rhabdomyoma
  • also seen in young patients
• rhabdomyosarcoma
  • large and heterogeneous mass
  • invasive
• myxoma
  • intracavitary rather than intramural
• metastases 
  • known primary neoplasm
  • less likely in young patients
  • multifocal masses